1. Field of the Invention
The field of the present invention relates to an enclosure for an electrical device generally, and more particularly to an interlockable enclosure cover for a switch, such as a circuit breaker, of which the following is a specification, reference being had to the drawings accompanying and forming a part of the same.
2. Description of the Related Art
In conventional electrical distribution and control systems, electrical switching devices such as circuit breakers for switching power ON and OFF are often enclosed in an housing having an openable cover. Such housings are typically of metallic or polymeric material and include a hinged door or removeable cover providing access to the interior of the housing. Non-limiting examples of conventional electrical device housings include switch enclosures, busway “busplugs”, motor control centers, panelboards, and switchgear.
In FIGS. 1A and 1B, a conventional switch device enclosure 100 is shown, having a switching device, such as a circuit breaker or switch 101 having an operating member 103 for switching power installed therein. A hinged cover or door 104 is openable via hinges 133a, 133b to provide access to the interior of enclosure 100. The door 104 is retained in a closed position by fasteners such as screws (not shown) and/or any number of releasable door-latching mechanisms having a biased releasable latch member 108 arranged to protrude through an aperture 110 in the door 104. Such latch members 108 are provided with an aperture 112 configured to receive a locking member (not shown) such as the hasp of a lock (not shown) for locking the cover 104 closed.
When closed, the door 104 prevents direct operative access to the operating member 103 of the enclosed switch 101. Operating handle 102 mounted external to the enclosure 100 and movable in the directions indicated by arrow 119 is configured to drive a mechanism including, for example, a moveable yoke 105, which in turn drives the operating member 103 of switch 101 for toggling the switch 101 from a power ON position to a power OFF position. Labels (not shown) having text such as “ON” and “OFF”, are positioned on enclosure 100 to correspond to operating handle 102 positions that likewise correspond to, and thus indicate, the state of the enclosed switch 101.
Various electrical standards require, as a safety feature, an interlock or latch mechanism to prevent opening of the door or removal of the cover while the enclosed switch is in the ON or conducting state. Prior art interlock assemblies 141 are conventionally configured to cooperate with a mechanism 142 driven by the externally-mounted operating handle 102 to prevent the opening of the door 104 while the enclosed switch 101 is in the ON or conducting state.
While safety latch assemblies for enclosures are generally known in the art, they have certain disadvantages. They are generally complex and expensive, often with a relatively large number of parts, and some permit closing of the cover 104 with the enclosed switch 101 in the ON position. This latter disadvantage can result in the enclosed switch 101 being in an ON or conducting state while the external operating member 102 position incorrectly indicates that the enclosed switch 101 is in an OFF or non-conducting state, thus resulting in a potentially hazardous condition.
It is desirable to provide an improved device configured to allow direct external operability of a switch or circuit interrupter installed in a housing, with a simpler, low cost apparatus to prevent opening and/or closing of the enclosure cover when the enclosed switch is in the “ON” position.